Early administration of tecovirimat shortens the time to mpox clearance in a model of human infection

Despite use of tecovirimat since the beginning of the 2022 outbreak, few data have been published on its antiviral effect in humans. We here predict tecovirimat efficacy using a unique set of data in nonhuman primates (NHPs) and humans. We analyzed tecovirimat antiviral activity on viral kinetics in NHP to characterize its concentration–effect relationship in vivo. Next, we used a pharmacological model developed in healthy volunteers to project its antiviral efficacy in humans. Finally, a viral dynamic model was applied to characterize mpox kinetics in skin lesions from 54 untreated patients, and we used this modeling framework to predict the impact of tecovirimat on viral clearance in skin lesions. At human-recommended doses, tecovirimat could inhibit viral replication from infected cells by more than 90% after 3 to 5 days of drug administration and achieved over 97% efficacy at drug steady state. With an estimated mpox within-host basic reproduction number, R0, equal to 5.6, tecovirimat could therefore shorten the time to viral clearance if given before viral peak. We predicted that initiating treatment at symptom onset, which on average occurred 2 days before viral peak, could reduce the time to viral clearance by about 6 days. Immediate postexposure prophylaxis could not only reduce time to clearance but also lower peak viral load by more than 1.0 log10 copies/mL and shorten the duration of positive viral culture by about 7 to 10 days. These findings support the early administration of tecovirimat against mpox infection, ideally starting from the infection day as a postexposure prophylaxis.


Introduction
Declared in July 2022 a public health emergency of international concern, mpox (previously known as monkeypox) has been reported in more than 80,000 cases worldwide [1].Classically, the virus is transmitted predominantly to human through direct contact with an infected animal, and less commonly between humans [2,3].However, in the 2022 outbreak, mpox has been predominantly reported among men who have sex with men [1].Little data are available on the natural history of mpox infection, and findings rely on scarce samplings from small cohorts [4][5][6].In a study conducted in Spain, 77 individuals were enrolled shortly after symptom onset and followed until viral clearance [7].Mpox was detected in various compartments, and viral replication was particularly high in skin lesions, with a median time to viral clearance of 25 days, and about 14 days to clear replication-competent virus.
Currently, tecovirimat is the most commonly used antiviral agent for mpox [3].Initially developed to treat human smallpox, tecovirimat demonstrated strong antiviral activity by blocking the VP37 protein in virus maturation and release from the infected cell [8,9].The drug pharmacokinetics (PK) and tolerance were assessed in animals and healthy volunteers to propose relevant dosing regimens [9,10], showing an oral bioavailability of 48%, higher with food intake, and high plasma protein binding (75% to 82%).Tecovirimat is metabolized mostly to 4-trifluoromethyl benzoic acid (TFMBA) with no pharmacologically active metabolites [11].Based on these findings, tecovirimat was approved by FDA in 2018 and by Health Canada in 2021 for the treatment of smallpox.The drug was later approved in 2022 by European Medicines Agency for the treatment of smallpox, monkeypox, cowpox, and vaccinia complications [12].However, only few data are available on its efficacy in mpox-infected patients [4,13].Several randomized, placebo-controlled, double-blind trials are ongoing, but the assessment of the virological and clinical benefits of tecovirimat will be hampered by the ethical challenges in conducting randomized trials as well as the rapid reduction in the number of cases in most parts of the world.
Here, we analyze by modelling data collected in NHPs infected with mpox, in healthy volunteers treated with tecovirimat, as well as in untreated patients infected with mpox, to predict tecovirimat effects at different dosing regimen on mpox viral dynamics in human skin lesions and guide its current use.
Viral kinetic model and parameter estimates.We used a target cell-limited model with an eclipse phase to fit observed viral dynamics in NHPs (Fig 1B, Materials and methods).The fitting process estimated the median within-host basic reproduction number R 0 = 3.94 (S1 Table ).The productively infected cell death rate, δ, was estimated at 0.3 per day.The estimate of p depends on T 0 , the initial target cell density, thus, only the product p×T 0 could be reliably estimated (2.5 × 10 8 copies/mL/day), with sensitivity analysis being performed (S2 Fig) .Estimating tecovirimat antiviral effect.We reconstructed tecovirimat concentrations in NHP plasma, C p (t), using a previously developed model [14].The model accurately reproduced dose-depending plasma concentrations (S3 Fig) .Next, in this model, the first-order rate constant between plasma and the effect compartment, noted k e0 (estimated at 0.004 per day), describes the temporal dissociation of the time course between plasma concentrations and its inhibitory effect.Accordingly, we estimated tecovirimat EC 50 , to 1.6 ng/mL, with sensitivity analyses being performed with the coefficient h fixed at different values (S4 Fig) .Alternatively, the concentration required to achieve the 90% antiviral effect, EC 90 , was equal to 14.4 ng/mL.Although tecovirimat rapidly achieved high concentrations in plasma, an effect compartment was needed to capture the time to achieve high efficacy at the effect site.Thus, at doses of 10 and 20 mg/kg/day, model predicted that a median of 8 and 4 days, respectively, is required to reduce viral production by more than 90% (Fig 1C).At steady state, the model predicted median antiviral efficacy of 84%, 94%, and 97% at doses of 3, 10, and 20 mg/kg/day, respectively.Accordingly, tecovirimat administration led to a rapid viral decline in all treated animals, with a median time to viral clearance of 25 and 20 days at doses of 10 and 20 mg/kg, respectively (Figs 1D and S1).

Tecovirimat PK/PD in humans
Assuming the same PK/PD relationship holds in humans, we next estimated the antiviral efficacy that can be obtained in humans.For that purpose, we relied on a PK model developed in healthy volunteers (S2 Table ) to predict drug exposure in both plasma (Fig 2A) and in the effect compartment at doses of 400 mg bid, 600 mg bid, or 600 mg tid.Concentrations in the effect compartment, C e (t), rise gradually to values ranging from 40 to 100 ng/mL depending on the dose administered, i.e., much higher than the estimated drug EC 90 , leading to similar antiviral efficacy for all doses (Fig 2B ).Accordingly, the antiviral activity took 3 to 5 days to reach 90% efficacy and, at steady state, achieved median levels of 98% for all dosing group.These predictions remained similar when considering large range of weights and recommended weight-adjusted doses (S5 Fig) .Modeling mpox viral dynamics in human skin lesions.Next, we characterized mpox kinetics in 54 non-antivirally treated individuals [7] for which the (putative) infection date had been identified (S3 Table ).We focused on skin lesions, with a total of 264 samples included in our analysis.The delay between infection and symptom onset ranged from 0 to 14 days, with a median of 6 days (IQR = 4 to 8) (Fig 3B).The time from symptom onset to first PCR varied between 3 and 66 days, with a median of 23 days (IQR = 12 to 34).Patients were all male and aged 23 to 88 years, with a median of 35.5 years (IQR = 31 to 45.5).

Viral dynamic modeling.
A target cell-limited model with an eclipse phase described well VL in skin lesions (Fig 3A).Viral dynamic parameters and their variability were estimated with good precision (Table 1).The visual predictive check (VPC) showed a central trend and predicted variability consistent with observed data (S6 Fig) .The loss rate of productively infected cells, δ, was equal to 0.64/day, corresponding to a half-life of infected cells of 25 hours (IQR = 22 to 30) in all patients.Similar to NHPs, with μ and T 0 fixed to frequently reported  ), and pharmacodynamic parameters estimated in NHPs (Table 1).Yellow: 400 mg bid; orange: 600 mg bid; copper: 600 mg tid.The model also estimated a median within-host basic reproduction number R 0 = 5.6.This implies that to be fully effective on viral kinetics, an antiviral treatment would require to be given before peak VL with an antiviral activity larger than 1 to 1/5.6 = 82% (see Materials and methods).In other words, any antiviral agent would need to reach concentrations above its EC 90 to substantially shorten the time to viral clearance.
Predicting tecovirimat antiviral effect on viral dynamics in humans.Finally, we predicted tecovirimat activity on mpox dynamics in patients, using model parameters estimated in NHPs and healthy volunteers, as well as in infected individuals.The analysis considered different 14-day tecovirimat dosing regimens, initiated either as immediate postexposure prophylaxis or upon symptom onset (Figs 4 and S8).Viral metrics prediction was also performed for EC 50 or Hill coefficient higher than identified in NHPs (S9 and S10 Figs).
Without treatment, mpox peaked in skin lesions in median at 8.0 log 10 copies/mL on D9 postinfection, becoming undetectable by qPCR in median on D29, and by viral culture on D16.Oral tecovirimat for 14 days given since symptom onset was predicted to reduce the median time from infection to undetectable virus by qPCR and by viral culture by 6 and 4 days, respectively, with a duration of positive viral culture shortened by 5 days, irrespective of the administered dose.As VL generally peaked shortly after symptom onset, the model predicted a minimal impact on median peak VL with a reduction by only 0.5 to 0.7 log 10 copies/ mL, and a probability of peak VL being below the infectivity threshold (meaning very low risks of contagiousness) between 8% and 18%, depending on the dose.Postexposure prophylaxis further reduced the median peak VL by 1.2, 1.4, and 1.5 log 10 copies/mL, respectively.Additionally, this strategy might reduce the median duration of positive viral culture by 7 to 10 days depending on the dose, while leading to a large proportion of individuals remaining noninfectious at all time, as suggested by a probability of peak VL below the culture threshold, equal to 26%, 40%, and 54% at dosing regimen of 400 mg bid, 600 mg bid, and 600 mg tid, respectively.

Discussion
Using data from infected NHPs and healthy participantsAU : PleasenotethatasperPLOSstyle; donotuseth treated with tecovirimat, as well as viral dynamics from non-antivirally treated patients, we provided a comprehensive insight in tecovirimat expected antiviral effect in mpox-infected individuals.Tecovirimat could shorten the time to viral clearance and the duration of positive viral culture, provided that treatment is initiated before viral peak (which occurs about 2 days after symptom onset), or even earlier, ideally as an immediate postexposure prophylaxis.This suggests potential benefits in shortening infectious periods following early administration of tecovirimat [7].
Bridging data from NHPs to humans is contingent upon several hypotheses.First, the experimental model of mpox infection in NHPs is more severe than in humans, with an extensive and prolonged viremia in all animals, compared to the transient and low-level viremia generally observed in humans [4,6,7].Additionally, the NHP model suggested that mpox infection could modify tecovirimat PK, requiring drug exposure analysis in clinical studies [10,14].Nevertheless, the model allowed us to precisely measure tecovirimat effect on viral replication and, hence, to estimate the concentration-effect relationship of tecovirimat in vivo.Data in untreated individuals originate from the largest prospective analysis of mpox dynamics so far [7].Viral replication was observed in several compartments, namely, oropharynx, semen, rectum, skin lesions, and blood.Unfortunately, only skin lesions showed sufficiently high viral replication to build a mathematical model and estimate viral dynamic parameters; therefore, our approach could not be used to predict dynamics in other compartments.As the infection date was known, we could reconstruct viral kinetic trajectories from infection to cohort inclusion, estimate the basic within-host reproduction number, R 0 , and obtain a PD target to effectively prevent viral replication.
The target cell-limited model used to characterize viral dynamics is well established and has been employed in many other acute viral infections, e.g., influenza, Zika, and SARS-CoV-2 [15][16][17][18].This model also assumes that viral clearance is mediated by target cell limitation, which is a very strong assumption.This might be incorrect for human mpox lesions as most of genital skin is left uninfected, even during severe infections [4,19].More complex models could also be relevant, in particular to understand how the immune response develops, in connection with symptom onset and/or infection resolution.As we did not have access to immunological data, we here made the conservative assumption that the immune response was constant over time, reflected by a loss rate of infected cells, noted δ.This may lead to underestimate the effect of early treatment and how it may synergize with innate immunity [17].Also, the model was not used to identify tecovirimat effects in other locations and might oversimplify how spatial constraint and innate immune effects impact virus spread.However, data suggest that tecovirimat is well distributed in reproductive compartments, indicating that it could also reduce the risk of sexual transmission [20].Lastly, the model focused on viral dynamics, but how this may translate in terms of symptoms and clinical evolution will need to be investigated.
Another important assumption is that the concentration-effect relationship in human skin lesions was predicted using data obtained with another mpox strain, Zaire 79, and blood viral kinetics.Recently, an in vitro EC 50 of 4.8 ng/mL has been identified for the 2022 strain [21], which is close to the value of 1.6 ng/mL (90% PI = 1.5 to 13.4 ng/mL) estimated with our model.Lacking data on tecovirimat in skin lesions, we hypothesized that drug concentrations evolved over time similarly in both infected humans and NHPs in the effect compartment with rapid accumulation in the effect compartment and a long half-life after treatment cessation.This will require further investigation by analyzing tissue distribution of tecovirimat in different locations, including skin, and how this may guide optimal treatment duration.In mice, tecovirimat was detected in all tissues 24 hours postdose and remained detectable until hours postdose [22].In humans, at steady state, tecovirimat concentrations in semen may exceed 50 ng/mL, leading to sustained mpox clearance from semen samples after the first week of treatment [20].Nevertheless, the EC 50 was reported based on an effect compartment, lacking pharmacological data to verify this part of the model.Consequently, it might be more clinically beneficial to propose plasma concentrations as a PK/PD target.To evaluate whether plasma concentrations are associated with antiviral efficacy in the effect compartment, using our model, we analyzed simulated plasma concentrations by groups of adequate antiviral efficacy and those remaining below the critical threshold.However, our model could not identify any differences in plasma drug concentrations between these groups (not shown).This prediction will need revisiting with upcoming PK/PD clinical results.
In conclusion, our analysis shows that tecovirimat at recommended dosing regimens could shorten the time to viral clearance and reduce the duration of positive viral culture.

Ethics statement
The NHP study was conducted in compliance with US FDA 21 CFR Part 58 (Good Laboratory Practice for Nonclinical Laboratory Studies).Exceptions to US FDA 21 CFR Part 58 include the manufacturing and analysis of the test article, which will be performed under GMP, and characterization of the test pathogen (MPXV).The protocol also complied with all applicable sections of the Final Rules of the Animal Welfare Act regulations (9 CFR Parts 1, 2, and 3) and Guide for the Care and Use of Laboratory Animals-National Academy Press, Washington, DC 1996 (the Guide).This study was conducted in LBERI's (Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico) AAALAC (Association for the Assessment and Accreditation of Laboratory Animal Care)-accredited facility.The study was supported by the Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health (contract HHSN266200600014C), and the Biomedical Advanced Research and Development Authority (contract HHSO100201100001C).
The study protocol of human viral dynamics [7] was approved by the Ethics Committee of the Hospital Germans Trias i Pujol (PI-22-156), and written informed consent was obtained from all participants before enrolment.All investigation were conducted according to the principles expressed in the Declaration of Helsinki.

Investigating tecovirimat concentration-effect relationship in NHPs
Study design.The experimental procedure and settings were described previously [23].In brief, 24 macaques (Macaca fascicularis) were included with age 2 to 4 years and weight 2.8 to 4.0 kg.On D0, all monkeys were infected with a lethal intravenous (IV) dose of 5 × 10 7 pfu of mpox Zaire 79 strain.All animals were randomized into 4 groups of 3 males and 3 females each that were administered vehicle or oral tecovirimat at 3, 10, or 20 mg/kg/day for 14 days (Fig 1A ), starting from D4.
Modeling viral dynamics in absence of treatment.A target cell-limited model was used to fit mpox viral dynamics (Fig 1B) [17,18,24].The model includes 3 types of cell populations: target cells (T), infected cells in an eclipse phase (I 1 ), and productively infected cells (I 2 ).Target cells infected at a constant infection rate β (mL/virion/day).After a mean eclipse phase of 1/k days, infected cells (I 1 ) become productively infected cells (I 2 ), producing virions at rate p, and are lost at a per capita rate δ.The virions generated can be infectious (V I ) with proportion μ, while the (1−μ) remaining proportion is noninfectious (V NI ).The total VL, measured in DNA copies, is the sum of infectious and noninfectious viral particles, both cleared at the same rate (c, for virions produced de novo).As inoculation was performed with a high IV dose, we added to the NHP model a compartment for the inoculum (Fig 1B) that distinguishes the injected virus (V s ) from the virus produced de novo (V I and V NI ) [25].Uninfected target cells (T) can be infected (I 1 ) either by infectious viruses (V I ) or inoculum (V s ).Virions from the inoculum are cleared at rate c i .Accordingly, the model can be written as follows (Equations 1): The basic within-host reproduction number R 0 , defined by the number of secondary infected cells resulting from one infected cell in a population of fully susceptible cells, T 0 , is defined by R 0 ¼ bpT 0 m=cd.
Tecovirimat pharmacokinetics in NHPs.Tecovirimat individual concentrations in NHP plasma, C p (t), were predicted using a previously developed PK model assuming a first-order absorption, with weight-and dose-dependent parameters (S2 Table) [14].
Predicting tecovirimat concentration-effect relationship.Based on its mechanism of action, tecovirimat is assumed to inhibit viral production p, and linked, not to plasma, but intracellular concentrations [9].Thus, the PK/PD relationship is characterized by a transfer constant k e0 between central and effect compartments dC e =dt ¼ k e0 ðC p À C e Þ, and the therapeutic effect, �ðtÞ ¼ C h e ðtÞ=ðC h e ðtÞ þ EC h 50 Þ, where C e (t) is the effect concentrations at instant t; h, the Hill coefficient, and EC 50 , the drug concentration producing 50% of the maximal effect.Hence, differential equations for V I and V NI are modified as follows (Equations 2): Assumptions on parameter values.To ensure parameter identifiability of the viral dynamic model, we fixed several parameters of the viral dynamic model.The clearance rates were fixed to 10 and 20 virions/day for virions produced de novo (c) and from the inoculum (c i ), respectively [25].As only the product p×T 0 is identifiable, we fixed the density of target cells, T 0 , to 10 5 cells/mL for a typical macaque plasma volume of 300 mL [17].Note that the value of T 0 was chosen to be plausible and does not affect our main findings regarding the basic reproduction number R 0 , the half-life of infected cells, and the antiviral effect [17].The number of nonproductively and productively infected cells at the infection time are set to 0 [I 1 (0) = I 2 (0) = 0].Constant k was fixed to per day (representing a mean eclipse phase of 6 hours).To evaluate our prediction reliability, sensitivity analysis was performed by varying fixed parameters c and c i between  virions/day.The Hill coefficient, h, was fixed to 1, followed by a sensitivity analysis on virological predictions with higher fixed values between [2][3][4][5]

(S4 Fig).
Model fitting strategy.We fitted the PK and viral dynamic models to data from all animals simultaneously taking a nonlinear mixed-effect modelling approach.All estimations were performed by computing the maximum likelihood estimator using the stochastic approximation expectation-maximization (SAEM) algorithm implemented in Monolix Software.Random effects with SD below 0.1 or associated with RSE >100% were removed using a backward procedure and kept when resulting in BIC increased by no more than 2 points.Goodness of fit was assessed by visually inspecting individual fits and residual scatter plots.
Model predictions.The final model was used to extrapolate antiviral efficacy of tecovirimat in NHPs at different dosing regimens at doses of 3, 10, or 20 mg/kg/day administered for 14 days, and this was compared to viral dynamics predicted in absence of treatment.Prediction intervals were obtained by sampling 1,000 simulated individuals in the estimated distribution of the population parameters.

Predicting PK/PD tecovirimat in humans
Predicting concentration-effect relationship of tecovirimat in humans.We used a pharmacokinetic model previously developed in healthy volunteers receiving different doses of tecovirimat to predict the plasma drug concentration of tecovirimat (S2 Table ).Using this model and the parameters characterizing the concentration/effect relationship identified in NHPs (i.e., k e0 and EC 50 ), we predicted tecovirimat antiviral efficacy over time under different dosing regimens in humans.A sensitivity analysis on predicted viral metrics, in which EC 50 or Hill coefficient can be higher in humans, was also performed to ensure the conservative approximation of in vivo efficacy (S9 and S10 Figs).Because all infected participants in our study were men (see below), the simulation focused on men.We used a similar weight of 78.4 kg for all individuals, which is the median value observed in healthy volunteers (see Results).Prediction intervals were obtained from 1,000 simulated individuals.
As an exploratory analysis, we also tested if weight could modify these predictions, relying on the dose adjustment guidelines of tecovirimat [14].

Modeling lesion viral dynamics in untreated patients
Study design and population.The study population was previously presented in detail [7].In brief, this observational prospective multicenter cohort included adults over 18 years without severe mpox infection (defined as requiring hospitalization), having symptom onset within the previous 10 days.In order to reconstruct viral dynamics, we only here analyzed the 54 individuals (all male) with known infection date (defined by suspected sexual intercourse with mpox-infected partner) and only focus on viral dynamics in skin lesions.VL in other locations (oropharynx, semen, rectum, and blood) were too low and transient to reliably estimate viral kinetic parameters (see Discussion).
Sample collection.Participants were required taking self-collected samples on Days 1, 8, 15, 22, 29, and 57 after the screening visit.All samples were analyzed to detect mpox DNA by qPCR, with a lower limit of quantification of 2.9 log 10 copies/mL [7].None of the samples with VL below 6.5 log 10 copies/mL had a positive viral culture, while the probability of positive culture was equal to 70% in samples with VL above 6.5 log 10 copies/mL, which is proposed as the threshold for infectivity [7].
Model building and parameter estimation.We used a similar structure for the viral dynamic model to fit to lesion viral dynamics as in NHPs.Because only the product of p×T 0 is identifiable, we fixed T 0 by assuming that a skin lesion of 1.0 cm in diameter has an average surface area of 50 mm 2 [26,27], and the density of human keratinocytes is 47,000 cells/mm 2 [28], which give an amount of 2.3 × 10 6 initial target cells.As only a fraction of these cells is actually susceptible to infection, we set this fraction to 10%, thus T 0 to 2.3 × 10 5 cells.The volume would be approximately 523 mm 3 , or 0.5 mL, assuming that a skin lesion is spherical.Finally, the proportion of infectious virus μ was fixed to 10 −3 , the median of values [10 −4 -10 −2 ] that were reported in the literature for other viral infections [15][16][17][18].Sensitivity analyses were performed to evaluate the impact of those assumptions, with fraction of sensitive target cells of 1% and 100%, distribution volume of 0.125 and 0.25 mL, and proportion of infectious virus μ of 10 −4 and 10 −2 .

Projecting the antiviral effect of tecovirimat on viral dynamics
Finally, we combined the PK and the viral dynamic models to predict VL in patients receiving tecovirimat.We considered that treatment initiation could either start immediately after infection (t = 0) or after symptom onset (using the same distribution for the incubation period as found in the data), and different doses of 400 mg bid, 600 mg bid, or 600 mg tid administered for 14 days.
To assess the impact of these different treatment strategies on viral dynamics, 1,000 individuals of 78.4 kg were sampled from the estimated distribution of the PK and viral dynamic parameters, and we calculated the following metrics in each individual: peak VL, time to undetectable virus by PCR (VL <2.9 log 10 copies/mL), time to undetectable virus by culture (VL <6.5 log 10 copies/mL), and duration of positive viral culture (duration of VL >6.5 log 10 copies/mL) [7].

Fig 1 .
Fig 1. Antiviral efficacy of tecovirimat in nonhuman primates (NHPs).(A) Experimental study design.(B) Model structure: Target cells (T) are infected by infectious viruses, which can be produced de novo (V I ) or part of the inoculum (V s ) at rate β.Infected target cells enter an eclipse phase (I 1 ); after a median time 1/k, after which they become productively infected cells (I 2 ) and produce p viruses per day and are eliminated at rate δ.Produced virus can be either infectious (V I ) with proportion μ or noninfectious (V NI ).Virions inoculated and produced de novo are cleared at different rates, noted rate c I and c, respectively.Tecovirimat is administered orally, absorbed at a first-order rate k a with a bioavailability F, and distributed in central (C c ) and peripheral (C p ) compartments.Drug transfer between 2 compartments is represented by constants k cp and k pc and elimination from the central compartment by constant k c0 .An effect compartment (C e ) represents the pharmacological effect site where tecovirimat inhibits viral production p from infected cells at an efficacy �. (C) Tecovirimat predicted efficacy over time.(D) Mpox plasma viral load predicted by the model.In (C) and (D), predictions are given as median and 90% prediction interval.Grey: no treatment; green: 3 mg/kg/day; olive: 10 mg/kg/day; orange: 20 mg/kg/day; dashed horizontal line: limit of quantification.https://doi.org/10.1371/journal.pbio.3002249.g001

Fig 3 .
Fig 3. Mpox viral dynamics in skin lesions of non-antivirally treated individuals (N = 54).(A) Viral load in skin lesions (circles) and model predictions (grey).Empty circles indicate data below the limit of quantification by qPCR (LOQ); red dashed lines indicate symptom onset, and horizontal dashed lines indicate the LOQ.(B) Distribution of the incubation period.(C) Distribution of the delay between predicted peak viral load and symptom onset.https://doi.org/10.1371/journal.pbio.3002249.g003

about 2
days after symptom onset (Fig 3Band 3C).Our analyses also predicted a median duration of positive viral culture in skin lesions of 10 days (IQR = 9 to 12) and a median time to viral clearance of 28 days after infection (IQR = 25 to 34).